Cement-burning apparatus.



.No. 879,448. PATENTED FEB. 18, 1908.

B. E. BLDRED.

CEMENT BURNING APPARATUS.

APPLICATION FILED DEC. 1, 1906.

4 SHEETS-SHEET l.

3 nven I 01 PATENTED FEB. 18, 1908. B. E. ELDRED. CEMENT BURNING APPARATUS.

4 SHEETS-SHBET 3.

MMM zrJvC APPLICATION FILED DEG.1, 1906.

Witness attoznug PATENTED FEB. 18, 1908.

Arm-879,448.

B. E. ELDRED. CEMENT BURNING APPARATUS.

APPLICATION FILED 1330.1 1906.

4 SHEETS-SHEET 4.

. Z ing up through the'kiln, Many other mate-.

rials frequiring application of high tempera- .tures are treated in the'same type of kilns the same way; as forexam le, insin- BYRONYE. ELDRED, or BRONXVILLE, NEW YQRK'. I ".Y

' CEMENT-BURMNG APPARATUS;

' To" all whom it may concern." p n 'Be it known that I, Br'RoN E. ELDRED, a citizen of the United States, ,.re siding at Bronxville, in the county otWestc'hesterand State of New -York, have invented certain new and useful Improvements in Cement- Burning Ap aratus; and. I do hereby declare' the following to-be fa full, clear, and

' exact description of the same, such as enable others skilled-in the art to which it appertains to make and use the same. his invention relates to cement burning apparatus, and consists in an organization of heating and other ap aratus adapted to'cong vert cement' matemeils into cement clinker and to perform other high tem eratureheau I mg operations; all as more in y hereinafter.

set forth and claimed. V In the current modern practice of pro; ducing cement clinker, .the raw materials,

generally clay and some form of calcium car-.

bonate, either naturally or artificiallymixed,

are. reduced to a dry powderand passed dow through a rotary inclined kiln in heats ingrelation to a flame and flame gases travel- 'tering or nodulizihg. iron ores. ntreating cement materials in such kilns, duringtheir slow. downward passagev through the kiln they undergo. a variety ofchanges, of which the most'iniportant are the calcination of the calcium carbonate ,to form lime a change'whioh occurs in the up er part of the kilnand the union of this hmewith clay and silicates to formclinker-an action which takes, kiln. For the sake of brevity,. these two reactions may be andare commonly, called calcining and clinkering respectively. Gal cining is an operation whichrequires a lar e amount of heat but needs only-a relativey ljow' temperature,-, being dependent indeed as much on the"composition of the gasesin contact with the calcining material as upon the sheer degree Lot heat. Clinkering on, the other hand absorbs little or no heat, possibly evolvingfsomeby the exothermic action of silica and alumina upon lime, but needs a relatively highfte'mperature to institute the reaction a temperature but littlebelow that which will melt down clinker or ruin the refractory linings of the kiln. Obviously a Specificatibnof Letters I'atent ip u umfiieanetea a1.190s. Sei-ialNm346i958.

lacefin the lower portion ofthe J Patentedreb.=is,ie0s.

very nice balance of temperature is required in. clinkering; 'a balance not at allrequired 1n calcining. Des itethelr diversethermal requirements, .bot' these operations-have been customarily performed in a single kiln working with a smgle' source ,of heat; this source of heat being usuallya. flame plume of powdered coal, carried in aerial suspension byan air jet, and burning in the mouthof the kiln. Powdered coal is one vofthe few cheap and .available fuels whichwill. afford the necessary high. temperature conditions for clinkering. In producing this tem era-- ture in the manner described, there.1s, ow- I ever, agreat loss of fuel, three .orfour times as much-being necessaryas should be theoretically required, Part of thisloss is due'kto the reat amount ofair which must be supplie ,both to insure the free combustionnecessary to develop the clinker fornn'n tern erature and. to supply thenatural draft of t e 1101 kiln and stack. There is usually a: violent .inrushot air on all sides of the flame plume, forming a-sort of sheath of relatively coolair.) This great amount'of air, to ether with. the excessive-amount of coalj w 'ch must. be =burned,'causes a'very violent rush ofgases'throughlthe kiln, ick ing' up much of the cemenumaterial asv list.

This dusting renders'impraeticable the use of the ordinary heat regenerating or recuperiating meansin the usual operation of cement In a previous patent, N o. dated Sept. 4, ,1-906, .1 have deseribed and claimed.

a process. of operating by Whieh= inany of these disadvantages areobviated and .a num "ber of new advantages gained; such process consisting. in splitting up the usual operation into a number ofdiscrete stages and performing each stage of heating in a separate a paratus vby-a separate sourceoi heat, eac such] source of-heat being particularly adaptedto meet. the thermal requirements of its particular stage. In another atent, No. 829,957, dated Sept. 4, 1-906, I avedescribed and claimed sundry types of apparatus'fadapted tojperform the stated process and others of like nature. The apparatus-,herein illustrated and described is intended to, carry out the process of said Patent No.-.829; 6, and constitutes a modification of ahdimprovement upon the apparatus of said Patent N 0.

829,957, being particularly designed to ,be"

used in altering existing cement burning apthe ordina is applied t en becoming merely a calcining paratus to operate in accordance with the lnventions of in said patents. By means of the apparatus erein described, when used in combination with theordinary kilns -of (such existing apparatus, all or substantially all of the sintering may be-done' in the special sintering kiln herein illustrated and described, kiln to whichsaid sinteringkiln kiln, delivering its calcines into the sintering kiln; but by so addin my special sintering to the existing ki and employing the latter simply as a calcining kiln, it ecomes possible to greatly increase therate of feed of the material through such latter kiln, thus greatlyl increasing the capacity of the plant as a w ole, with a proportionate diminution of theamount of coal burned per unit of raw material;and other important advantages are likewise realized.

I The apparatus herein described may also be used in other operations involving -gressive heatingmaterials to hi h but efinite temperatures, as for examp e the nodulizing of 1ron ores.

In the sintering or clinkering kiln herein described,;instead of producin the necessary hi h temperature for'sintering yacoal flame, as has been the common practice when both operations have been carried out in the same kiln, I produce it with a producer gas flame may even be evolution of heat to some extent, the amount of combustible required to heat a separate clinkerer is only that which will suffice to raise the temperature of the calcines to the clinkerin point-a small amount; and that which Wlll compensate for radiation losses plus heat carried away in the clinker and discharged gases. The total of the heat losses by radiation and by heat carried away by the clinker is small; and by regeneration or recuperation of the entering air, as herein described, the loss by heat carried away in the'issuing gases is also made small; so that the amount of combustible required in the clinkerer is correspondingly small. So to speak, the heat in the clinkerer is almost static. This small amount of hi h temperature heat, I have discovered, can e easily, chea ly and readily produced by the use of a sure. 1 gas producer deliverin hot gas directlyfrom the producer into the c inkerer, and b the use of a regjqnerator or recuperator w 'ch heats to a 'gh temperature the air required for the combustion of such gas. A regenerator is here practicable both because the clinkerer works only on calcined material already heated almost or quite to it's sintering temperature,"and hence not inclined to dust and because of the special Way the clinkerer operates, whereby the carryin of dust into the regenerator is substantia y avoided. In the described arrangement of apparatus, the ordinary kiln being converted '1nt0 a simple calciner high efficiency may be attained with the coal burned and the amount ofcoal' per unit of raw material being reduced, with a given speed of travel of such material through the kiln the rush of hot gases is much diminished with a concomitant diminution in thetroubles arising from dusting. And as the consum tion of coal in feeding the clinkering kiln is very little, t 0 total amount of coal required ,for a barrel of cement is much reduced.

roducer of t e I The clinkerer. which I emplo as above it described, consists of a relative y short rotar inclined kiln, lined with refractory materlal and provided with a hood substantially sealing. the same at the upper end, the lower end of said kiln being open but fitting within. the hood of a regenerator hereinafter described. The inclination of the kiln may be due to its having an axis of rotation inclined with respect to the true horizontal, or

to a taper of the interior wall of the kiln.

The calcines, coming from another source, as above described, enter the, upper or closed end of said clinkerer, and after being sinter'ed in such kiln are discharged as finished clinker at the lower endof such kiln- A gas conduit leading as directly as practicable from a gas producer and arranged to permit as little as possible loss of heat from-the hot gas delivered by the producer, discharges such gas, more or less axially into the clinkerer. On either side of this conduit are ducts commu-' nicating with a special regenerative apparatus, comprising twin regenerators arranged to be heated alternately by the hot gases issuing from the kiln and to impart heat alternately to the entering air; the arrangement being such that the entering as andair currents enter the clinkerer side y side, mingle therein and burn, the flame gases and products of combustion'rec'urvin and passing out at the same end of the ki 11 at which the producer gas and airentered,'but through -a different duct; the two regenerators being operatedin alternation, of course, one being heated by the passage through it of the hot.

issuing gases, while the other is imparting heat to the entering air, the regenerators being reversed or exchanged, as to function, from time to time. But the regenerating apparatus is so constructed that there are no reversing valves exposed to high temperature gases, and that the'direetion of flow of the regeneraflow of the products of combustion outward through'tlie regenerator, so that there is a maximum interchange of heat and the prodnets of combustion issue relatively cold; one

and the same end of each regenerator being always relatively cold and the other end relatively hot.

The accompanying drawings illustrate one embodiment of my invention.

In said drawings: Figure 1 shows diagrammatically and in vertical section a gas producer, regenerator apparatus and clinkering kiln arranged and constructed according to my invention, and also shows an ordinary cement kiln arranged to deliver calcines to said clinkering kiln; the section being taken on the irregular section line wr of Fig. 2. Fig. 2 shows diagrammatically-and in horizontal section, the said producer, regenerator apparatus and clinkering kiln, the

' section being taken on the irregular section line shown slightly inclined.

yy of Fig. 1. Fig. 3 is a detail section similar to Fig. 1, but illustrative of alternative means of heating the calcining kiln. Fig. 4 shows a transverse vertical section through the regenerator apparatus, taken on the irregular section line 22 of Fig. 1. Fig. 5 is a detail top of driving and speed-changing and reversing mechanism for the clinkering kiln.

In said drawings, 1 designates the said clinkering kiln.

t is a short barrel kiln, the axis of which, in Fig. 1, is substantially horizontal, though in Fig. 3 said axis is The interior surface 2 of the lining f the kiln isshown, in

both cases, as a tapering or approximately conical surface, so that, in so far as the feeding of material through the kiln, both kilns are in effectinclined; the effective inclination of trated-f for example, in Fig. 1.

the kiln of Fig. 3 being the sum oiboth inclinations mentioned. It is obviously possible to make either inclination sufiiciently greatto make the other unnecessar ,as illus- The kiln having a truly horizontal axis is of course driven as hereinafter described, and (lIIVlIlg' a worm 7 on the klln.

"the better form in so far as mounting for rotation and driving is concerned difference is not great.

"forms of kiln mounted in the customary manner, on grooved rollers though the I have shown both 3 engaging bearin rings 4 on the kiln, the latter being arrange( tobe rotated by a worm 5 on a shaft 6 The kiln shown in Fig. 1 has at its upper end-a housing 8 substantially closing such end of the kiln, while in Fig. 3 the equivalent and-alternative construction of a kiln end integral with-the barrel of the kiln is shown. Suitable means for feeding calcines intothe kiln are provided, 'as for example a-lhopp'er Sand screw-conveyer 10 entering the kiln axially. At its lower end the kiln is open, butfits within a hood or housing 11 of the regenerating apparatus 12.

The gas producer,-13 is placed as near as practicable to the regenerating apparatus, being in fact inclosed within the same side walls, the third side of said producer being the wall 14 separating it from the regenerators, and the fourth side an inclined wall 15 suitably supported. In the space behind said wall are air admission tubes 16 adapted to be closed at thetop by valves 17 said tubes connected at the bottom to theregenerator passages 23' hereinafter mentioned. 18 designates the usual ash-pit, 19 the usual blast pipe, and 20 the usual twyers. The gas exit duct, or conduit, 21, for conveying the gas from the roducer to the kiln, passes over the top of the regenerating apparatus, being in factbuilt into the regenerator structure, its walls being of non-conducting material.

There are twin regenerator chambers, 22, containing the usual fillin of brick checkerwork or the like, each such chamber having at its lowerv end a assage'28 connecting with the stack 24, and having at its upper end a down-dip duct 25 lea ing to the interior of iln 1, the orifices of said ducts 25 being on either side of the gas supply passage 21. A butterfly valve 26 is rovided for controlling the connection of th stack.

27 designates an ordinary cement kiln, such as are nowcommonly used both to calcine and to sinter the material; it being my intention that my 'im roved clinkering kiln shall be added to suc ordinary cement kiln, the latter then being used simply as a calcining kiln, the temperature, flame conditions, rate of feed, and rate of supply of material being regulated so that the work done in kiln 27 is mainly or entirely calcining the calcined material being delivered from kiln 27 into hopper 9. In so adding my clinkeringkiln to an existing cement kiln I make such changes in e regenerator passages 23 to the the material-feeding devices of the latter, and

the driving mechanism thereof, as enable a much greater amount of material to be fed into the kiln and to enable it to be driven at much greater speed; for I find that when only calcining is to be done in kiln 27 ,-for the same amount of fuel burned it is capable of treating a much greater amount of material and .of effecting calcination thoroughly while the materialis'fed through it at much higher speed than is advisable when both calcining and sintering are performed in kiln 27. Most present cement kilns are provided with pulverized coal burners, and such burners may be retained, as indicated in Fig. 3,, in which such a burner, 28, is indicated in connection with kiln 27 there shown; it being possible to use the ordinary burner Without alteration.

. safer, and

But preferably I provide the calcining kiln with a burner using producer gas, such as the gas burner 29, Fig. 1, for example; doing so because producer gas is a much cheaper, more convenient fuel, and its flame may be regulated with greater nicety and through a greater range. The operation of the apparatus is as follows :-Calcining kiln 27 eing in operation and delivering calcines into hopper 9, said calcincs are delivered by conveyer 10 into kiln 1. Hot producer gas is passing directly from producer 13 through interior of kiln 1,,and air is passing through the lower air passage 23 of one of the twin regenerators up through the checker-work of such regenerator and through the passage 25 of that regenerator into kiln-1, there encountering the producer gasfrom duct 21 and burning the same. The .flame plume is projected well toward the upper end of the kiln and then the flame gases recurve and pass out through the other passage 25, down through the other regenerator 22, and thence through the other lower passage 23 and out through the stack. From time to time the butterfly valve 26 and air valves 17 are'operated to change the functions of the two rcgenerators, that re'generator which has .been heating the entering air current now receiving the issuing gases and being heated thereby, while that regeneratorwhich has previ ously been heating up, now giving oif its heat to the entering air. To so reverse the action of the regenerators, the butterfly valve26 is reversed and the valve 17 of the passage 23 whichis so connected to'the stack is closed,

and the valve 17.0f the other passage 23 opened. It will,be seen that the. entering air first encounters that portion of the regenerator from which during the heating up operation, the products of combustion lssue, and which therefore has the lowest temperature, and that the entering air issuesfrom that end of the regenerator which, during the heating up operation, receives the products of combustion and consequently has the highest temperature. This insures maximum exchange of heat and at the same time permits an arrangement of passages and valve whereby said valve is not exposed to hot gases. Furthermore, the direction of flow of the entering air through the regenerator being opposite thatof flow of the issuing gases through the regenerator, there is a strong tendency for any dust carried out from the kiln by: the issuing gases, to be carried back into the kiln by the entering air current when the operation of the regenerators is neXt reversed; the action of the air currents therefore, tendin to keep the regenerators clean and freev rom dust; a very important point. Collection of dust in the regenerators is further guarded againstby the down-dipping passage 25, through which duct 21 into the the products: of combustion pass .before entering theregenerator, there being a strong tendency to throw out an dust in the roducts of combustion, at t e bottom 0 this passa e. Cleaning doors 30 are commonly provi ed at, the bottom of passa e 25. Pre erably, thou h not necessarily, t c direction of rotation o kiln 1 is changed when the action of the regenerators is reversed, so that the gases entering the kiln, which of course have-the higher temperature, may pass in close proximity to the upturning side of the kiln, against which, of course, the bulk of the sintering material tends to lie; the issuing gases then passing out along the downturnin side of the kiln. When. thisis the case, t e tendency of the air currentsis as'a whole, to carr any dust back into the kiln. To permit drlving the kiln at any desired speed and in either direction, I have shown in Fig. 5, familiar speed changing and. reversing mechanism arranged to' drive shaft 6, comprising reversely arranged friction cones 31 and 32, and an interveningband 33 with means 34 for shifting the same longitudinally, and the familiar straight and crossed belt reversing device35. But any suitable reversing and speed changing device may be employed. I

The producer gas is not'passed through the regenerator,because as said gas issues from its producer it is already quite as hot as necessary, and if conducted as directly as possible to the kiln through heatinsulating passages, it suffers practicallyno'cooling, The entering air current is heated up by'the' regenerator and thus acquires a high'temperatureadapting it to produce in the kiln a high temperature with cheap producer gas of low thermal value. I i

The sintering operation be ing'rapid, the clinkering kiln 1 may be quite short, as shown and yet have a high capacity; except for its short length it would hardly be practicable to produce the inclination-of its walls necessary for feeding the material, by merely tapering said walls; but its shortlengthmakes this possible. Substantially the entire length of ordinary kiln, 27, being now available for calcining only, said kiln is now able to effectively same necessity. for careful and kilful regu1a tion of flame condi ions; a I

. The proportions of the clinkering kiln are prefera ly about as shown i. e. with a length not much greater than its diameter. Its internal length should not be much more than twice its diameter internally since .a

long narrow kiln would not permit the normal development of the recurving flame throughout and clinkering temperatures wouldnot be attained beyond the flame zone, makin the upperpart of such a longnarrow kiln su stantially useless for the present puroses. And the upper-end should beformed y a sealing Wall, substantially sealed against exit of gases, cooperating in shape with the kiln walls to permit such normal develop-- ment of the recurving flame, this wall being either integral with the kiln walls, as in Fi 1, and revolving therewith, or closely fitting against such kiln walls, as shown in Fig. 3. Preferably it is given a basin-like curve as sharp corners at the meeting of the kiln walls and end wallwould interfere with the normal development of the flame.

One important advantage of the tapering clinkering kiln as shown, for example, in F dust jet, either by awood fire built in its lower end, as commonly employed, or by a roducer gas burner like that shown on the iln 27 of Fig. 1, but portable, said burner being removed, and the coal dust burner substituted, if the kiln is well heated. But, as above stated, for economical reasons it appears desirable to heat both kilns by a producer gas flame.

By operating the regenerators in the man ner described, a very. eflicient exchange of heat from the outgoing products of combustion to the entering air is effected and the gases are so cooled by the time they reach the butterfly valve as not to injure the latter. The clinker discharged from the kiln contains much heat and this heat may be used to advantage for heating up the air supplied to the calcining kiln. Therefore I show in Fig. 1 the clinker discharged into a clinker it 36. Air to support combustion in the cal dining kiln is drawn from this it and is led by passage 37 to the calcining liiln.

What I claim is 1. A clinker making apparatus comprisin in combination a rotary cement kiln provided with coal firing means adapted to produce relatively low calcining temperatures therein and a regeneratively operating clinkering kiln receiving calcines therefrom.

2. A clinker making apparatus comprising in combination a rotary cement kiln provided with firing means adapted to produce relatively low calcining temperatures therein, and a rotary clinkering kiln provided with means for withdrawing products of combustion at its clinker discharge end and with gas firing means also at the clinker discharge end.

3. In a clinker making apparatus, a rotary inclined clinkering kiln provided With a sealing wall closing its upper end, means for introducing calcines therethrough, means for withdrawing clinker at its lower end, and gas firing means and means for withdrawin products of combustion, both located at sai lower end.

4. Clinker making apparatus, comprising in combination a rotary inclined calcining kiln and a rotary clinkering kiln receiving calcines therefrom, said clinkering kiln being provided with gas firing means adapted to produce a gasflame entering and leaving said iln at the clinker discharge end.

5. In clinker making apparatus, a rotary inclined clinkering'kiln rovided with a sealing wall at its upper end substantially closed against exit of gases and having means for introducing calcines therethrough and having means for introducing a gas flame and withdrawing products of combustion from the lower end.

6. Clinker. making apparatus comprising in combination a rotary inclined clinkering kiln provided with a sealing wall at its upper end substantially closed against exit of gases and having means for introducing calcines therethrough and also provided with an open lower end, a twin regenerator abutting against said lower end and gas firing means also abutting against said lower end.

7. Clinker making aparatus, comprising in combination a rotary inclined clinkering kiln provided with a sealing wall at its upper end substantially closed against exit of gases and having means for introducing calcines there- 'through and also provided with an open lower end, a gas producer having a gas conduit terminating within said open end, and a twin regenerator abutting against said open en 8. Clinker making apparatus, comprising in combination a rotary inclined clinkerin kiln having an open lower end, a sealing wall at its upper end, substantially closed against exit of gases and having a curving cavity registering with the internal kiln walls, a gas producer a heat insulated conduit delivering hot gas from the producer within said lower end, a twin regenerator abutting against the lower end, and twin conduits from the regenerators opening into the kiln on either side of said gas conduit.

9. Clinker making apparatus, comprising in combination a rotary inclined kiln, means for rotating the same, means for changing the direction of rotation, axial means for directing and burning a current of hot gas into the lower end of the kiln, and means for withdrawing products of combustion alternately from right and leftof said axial gas burning means.

10. In clinker making apparatus, a rotary inclined kiln having a sealing wall at its upper end provided with a curved cavity registering with the internal Walls of the kiln means for delivering solid material therethrough No. 879,449. I PATENTED FEB. 18, 1908. E. S. ENSIGN.

CALCULATING MACHINE.

APPLIOATION IILED MAY 3. 190B.

12 SHEETS-SHEET 1.

w 3 Inventor.

1, nesses.

' Emu S. Ensign. (2%; 5M fMW-@Z Attorney 

